hevansrv7a
Well Known Member
Thanks, Bob.
I think Bob came up with the best cost-benefit ratio in speed mods ever. I taped the gaps in the elevator leading edges which provide access to the attach bolts, four in all, top and bottom. I used HVAC sliver tape, a very thin and very sticky tape. I also covered the holes in the underside of the wing where the tie downs go. Cost what - ten cents at most?
The conditions for testing were not ideal, but at a minimum I gained 2-3 knots of TAS tested at a density altitude of 3000'. When we get a break in the Michigan WX I'll try to do a better test, but this is 2-way GPS verified. 177 KTAS versus previous best of 174 or 175 using a 3-way GPS test at DA of 8000 or more. It might have gone a little further, but I ran into my upper limit that I programmed into the autopilot! It kept cutting out with a warning and the air was too unstable for me to hold it well in level flight for this purpose.
The RPM was pretty much the 2650 I always get a full throttle.
Now I'm trying to think of a way to get this improvement with something more permanent and more attractive than silver tape.
I think Bob came up with the best cost-benefit ratio in speed mods ever. I taped the gaps in the elevator leading edges which provide access to the attach bolts, four in all, top and bottom. I used HVAC sliver tape, a very thin and very sticky tape. I also covered the holes in the underside of the wing where the tie downs go. Cost what - ten cents at most?
The conditions for testing were not ideal, but at a minimum I gained 2-3 knots of TAS tested at a density altitude of 3000'. When we get a break in the Michigan WX I'll try to do a better test, but this is 2-way GPS verified. 177 KTAS versus previous best of 174 or 175 using a 3-way GPS test at DA of 8000 or more. It might have gone a little further, but I ran into my upper limit that I programmed into the autopilot! It kept cutting out with a warning and the air was too unstable for me to hold it well in level flight for this purpose.
The RPM was pretty much the 2650 I always get a full throttle.
Now I'm trying to think of a way to get this improvement with something more permanent and more attractive than silver tape.